Learning here, thanks Ian and Don, hope I am not hijacking the thread.

If I let the logs dry to about 20% (the logs I just finished practicing on with my mill were at that avg level after being out in the open for years, according to my moisture meter) would that reduce the chances of problems sufficiently, or do we need to go farther than that, or simply fall back on milling first and then letting the wood dry?

I'd air dry them down to ambient - 15% and I would put a lap joint or t&G. Only if you were really pressed for time would I use them at 20%. Probably 6 months to a year to get to 15% would be my guess. I'm not a pine expert. I wouldn't do this with hardwood. I'd want it to be down to 15% for sure before using them.

Logged

Anything someone can design, I can sure figure out how to fix!If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

I used green 2" x 7" for the 1st and 2nd floor of my daughters tree fort, nailed down green. They shrunk on the edges and left 1/4" gaps or so, but mold wasn't an issue. Now that they have dried for a year or so, I'm going to use deck cleaner on them and stain them. A couple nails came loose, but that's on the boards that I inadvertently stuck with the grain the wrong way and they curled up on the edges.

Some more wood stuff, wood doesn't begin shrinking until it begins dropping below fiber saturation point, around 28% for most woods but as low as 20% for some. Above that point the free moisture that is leaving is just water in the cell cavity. As the bound water that is within the fibers of the cell walls leaves, only then do the fibers move closer together and shrinkage begins. So one way to think about it while reading the shrinkage tables is, if they are saying the species averages 8% tangential shrinkage from green to oven dry do not think that at 20% you have undergone 4/5 of the shrinkage from 100% to oven dry, rather think "I'm about halfway between 28% and 12%". In an open shed here in VA you will reach equilibrium moisture content around 12% just air drying. The lower parts of a barn without critters would be similar, as you go up there is more heat so lower RH and a lower EMC. I move shed dried wood to the upstairs of the barn to drive off a little more moisture. If it has a dirt floor and critter moisture the RH and EMC will rise. In my house in the winter wood will bottom out around 8%. Drying rate depends on species, RH, temp and airflow. 1" pine shed drying will be at emc in the summer in a few months with good airflow, white oak will get there the next summer.